May 1
edit2010: Record flooding began in Tennessee, eventually killing 16 people.
May 2
edit2009: An avalanche killed six hikers in Sölden, Austria.
May 3: Start of National Hurricane Preparedness Week 2020
edit1986: The GOES-G weather satellite, intended to replace the GOES 5 whose main imaging instrument had failed, was destroyed when the Delta 3914 rocket intended to deliver it failed to reach orbit due to an electrical fault.
May 4
edit2002: The Aqua weather satellite was launched into orbit.
May 5
edit1950: Known locally as "Black Friday", heavy precipitation caused the already swollen Red River to breach several dikes, causing disastrous flooding in Winnipeg, Manitoba.
May 6
edit1975: An F4 tornado struck Omaha, Nebraska, causing more than $1 billion (1975 USD) in damage.
May 7
edit1840: The Great Natchez Tornado struck Natchez, Mississippi, killing at least 317 people.
May 8
edit2009: A severe derecho blew across a large part of the United States, spawning 39 tornadoes and killing six people.
May 9
edit2007: Subtropical Storm Andrea formed off the coast of Florida, causing high winds which contributed to major brush fires.
May 10
editMay 11
edit1970: Seventeen years to the day after the deadliest tornado in Texas history, another tornado struck downtown Lubbock, Texas, killing 26 people. It was the only F5 tornado in history to strike a skyscraper, which had its steel infrastructure twisted by the storm.
May 12
edit1970: Severe floods began in Romania, eventually killing more than 200 and leaving more than 250,000 homeless.
May 13
edit1980: A strong tornado devastated downtown Kalamazoo, Michigan.
May 14
edit1991: The NOAA-12 weather satellite was launched into a polar orbit from Vandenberg Air Force Base, California.
May 15: Start of the East Pacific hurricane season and end of the Mauritius and Seychelles cyclone season
edit1887: A tropical storm formed southeast of Bermuda. This storm would be the first of four off-season tropical cyclones which would form in the Atlantic Ocean that year, the most in recorded history.
May 16
edit2004: Typhoon Nida reached category 5 intensity just east of the Philippines.
May 17
edit1896: A tornado outbreak killed dozens in Kansas and Nebraska.
May 18
edit1986: Cyclone Namu, the worst tropical cyclone ever to affect the Solomon Islands, killed 150 people as it passed through the island nation.
May 19
edit1997: A tropical cyclone made landfall near Chittagong, Bangladesh, killing more than 1,000 people.
May 20
edit2013: An EF5 tornado struck the heart of Moore, Oklahoma, killing 24 people, including seven children at an elementary school.
May 21
edit1953: A deadly tornado killed 2 people in Port Huron, Michigan, and crossed the St. Clair River into Canada where it killed 4 more people in Sarnia, Ontario.
May 22
edit1981: The GOES 5 weather satellite was launched. Part of the Geostationary Operational Environmental Satellite program, GOES 5 would provide weather forecasting data to the United States until its main imaging instrument failed in 1984.
May 23
edit1982: Tropical Storm Aletta reached peak intensity off the western coast of Central America. Aletta brought more than 50 inches (1,300 mm) of rain to parts of Honduras and Nicaragua, causing flooding that killed more than 300 people.
May 24
edit2001: A tropical cyclone reached peak intensity in the northern Indian Ocean with a central pressure of 932 millibars (27.52 inHg). At the time it was the strongest tropical cyclone on record in that region, and would eventually kill hundreds upon landfall in the Saurashtra region of India.
May 25
edit2009: Cyclone Aila struck Bangladesh, killing more than 300 people.
May 26
edit1972: Subtropical Storm Alpha reached peak intensity east of Savannah, Georgia, where it would make landfall the next day.
May 27
edit1997: The Jarrell tornado completely wiped out the Double Creek Estates, killing 27 of 131 residents.
May 28
edit2012: Tropical Storm Beryl made landfall near Jacksonville Beach, Florida, with maximum sustained winds of 55 knots (65 mph; 100 km/h). Beryl was the strongest off-season Atlantic tropical cyclone on record to strike the United States.
May 29
edit2008: Tropical Storm Alma formed just off the coast of Costa Rica at 86.5º W, the easternmost Pacific tropical cyclone on record. Alma was also the only known tropical cyclone to strike the Pacific coast of Nicaragua.
May 30
edit1959: Tropical Storm Arlene made landfall near Lafayette, Louisiana, bringing more than 10 inches (25 cm) of rain to parts of the northern Gulf Coast of the United States.
May 31
edit2013: The widest tornado ever recorded struck the area near El Reno, Oklahoma, killing 8 people, including renowned tornado researcher Tim Samaras.